The US vice-president and presidential candidate, Al Gore, showed off his new running mate yesterday and declared that their Democratic ticket would "tear down a mighty wall of division" by making Senator Joseph Lieberman the first Jewish vice-president of the United States.

Mr Gore compared the quest to the election of John F Kennedy as the first Roman Catholic president in 1960. He said the Democrats had made history then, and with Mr Lieberman's nomination, would do so again, 40 years later.

Mr Lieberman praised Mr Gore for choosing him. He said the vice-president had showed his faith in the tolerance, diversity and "basic fairness of the American people" by choosing him.

Yesterday Mr Lieberman's wife, Hadassah, talked of her parents' survival in Nazi concentration camps during the second world war.

Mr Gore presented his choice of running mate to the crowd, many of whom waved newly printed Gore-Lieberman campaign placards, hugged him and then praised him, concentrating on the issues they have shared in the Senate and since.

"I am proud to stand by your side," Mr Lieberman told Mr Gore in return. The senator began with a personal invocation: "Dear Lord, maker of all miracles, I thank you for bringing me to this extraordinary moment in my life."

The first Jew chosen for a major party ticket, he thanked Mr Gore "for making this miracle possible for me and breaking this barrier for the rest of America forever".

"You know, there are some people who might actually call Al Gore's selection of me an act of chutzpah," said Mr Lieberman, using the Yiddish word for audacity.

Then he showed some of his own, scoffing at Republican suggestions that his position on issues was similar to those of their party's presidential candidate, George W Bush.

"With all due respect, I think that's like saying the veterinarian and the taxidermist are in the same business because either way you get your dog back," Mr Lieberman said.

He promised to work with Mr Gore "to renew the moral centre of this nation". That message of morality has been Mr Lieberman's trademark; he was one of the first Democratic senators to publicly rebuke President Bill Clinton in the Monica Lewinsky affair.

Mr Lieberman called Mr Gore "a man of family and a man of faith".

"He has never wavered in his responsibilities as a father, as a husband and, yes, as a servant of God Almighty," he said.

Mr Lieberman is one of the president's sharpest critics in the Democratic party.

Although differences have been noted in Mr Gore and Mr Lieberman's stances on some issues, Mr Gore said the real gap was between them and the Republicans.

"It comes down to this: Joe and I are fighting to see to it that our prosperity benefits working families and not just the few," Mr Gore said.

Republicans quickly sought to find differences they can exploit between Mr Gore and Mr Lieberman, including differences on issues such as social security and school vouchers. AP